chore: migrate self-distribution links from GitHub to self-hosted Gitea

GitHub accounts suspended; all first-party distribution now served from
git.881218.xyz/rogue/NexusGate (Gitea):
- raw:  /rogue/NexusGate/raw/branch/<branch>/<path>
- release assets and source archives under the same repo path
- scripts gain a GIT_BASE variable built from NG_REPO (default
  rogue/NexusGate); NG_REPO/NG_BRANCH/--repo/--branch semantics unchanged
- panel enrollment/uninstall commands in public/app.js point at Gitea raw
- install.sh/nexusgate.sh/agent-singbox.sh stats source previously
  defaulted to the upstream repo (a2899882); defaults now this repo
Upstream dependency references (sagernet/sing-box Go module) untouched.

scripts/agent-install.sh

@@ -1,12 +1,14 @@
 #!/usr/bin/env bash
 set -Eeuo pipefail
 
-REPO="${NG_REPO:-aaaamoooo/NexusGate}"
+REPO="${NG_REPO:-rogue/NexusGate}"
 BRANCH="${NG_BRANCH:-main}"
+# 自建 Gitea 分发基址（raw / release / archive 均由此拼装）
+GIT_BASE="https://git.881218.xyz/${REPO}"
 # Agent 实现：默认 go（静态二进制，节点机不再需要 Node.js）。
 # NG_AGENT_IMPL=node 可回退到旧版 Node agent（agent/agent.js + nodejs 包）。
 AGENT_IMPL="${NG_AGENT_IMPL:-go}"
-# Go agent 二进制所在的 GitHub Release tag
+# Go agent 二进制所在的 Gitea Release tag
 AGENT_RELEASE="${NG_AGENT_RELEASE:-agent-v0.6.8}"
 CONTROLLER=""
 TOKEN=""
@@ -14,14 +16,14 @@ TOKEN=""
 die() { printf '错误：%s\n' "$*" >&2; exit 1; }
 info() { printf '\033[1;36m[NexusGate Agent]\033[0m %s\n' "$*"; }
 
-# NG_LOCAL_SRC 指向本地源码目录时跳过 GitHub 下载（本地改动尚未 push 时用这个）
+# NG_LOCAL_SRC 指向本地源码目录时跳过远程下载（本地改动尚未 push 时用这个）
 fetch() {
   if [[ -n "${NG_LOCAL_SRC:-}" ]]; then
     [[ -f "${NG_LOCAL_SRC}/$1" ]] || die "NG_LOCAL_SRC 目录缺少 $1"
     cp -a "${NG_LOCAL_SRC}/$1" "$2"
   else
-    # 加时间戳破坏 GitHub raw 缓存，避免拉到旧版
-    curl -fL --retry 3 "https://raw.githubusercontent.com/${REPO}/${BRANCH}/$1?t=$(date +%s)" -o "$2"
+    # 加时间戳破坏 raw 缓存，避免拉到旧版
+    curl -fL --retry 3 "${GIT_BASE}/raw/branch/${BRANCH}/$1?t=$(date +%s)" -o "$2"
   fi
 }
 
@@ -50,7 +52,7 @@ fetch_agent_binary() {
   if [[ -n "${NG_LOCAL_SRC:-}" && -f "${NG_LOCAL_SRC}/agent-go/nexusgate-agent-linux-${arch}" ]]; then
     cp -a "${NG_LOCAL_SRC}/agent-go/nexusgate-agent-linux-${arch}" "$out"
   else
-    curl -fL --retry 3 "https://github.com/${REPO}/releases/download/${AGENT_RELEASE}/nexusgate-agent-linux-${arch}" -o "$out"
+    curl -fL --retry 3 "${GIT_BASE}/releases/download/${AGENT_RELEASE}/nexusgate-agent-linux-${arch}" -o "$out"
   fi
   [[ -s "$out" ]] || die 'Agent 二进制下载不完整'
 }